Kinetic Technology


30W PoE PD and DC-DC Controller

Topology: Buck
Input Voltage (min.): 41.00 V
Input Voltage (max.): 57.00 V
Switching Frequency (min.): 80.00 kHz
Switching Frequency (max.): 550.00 kHz
Output 1: 11.82 V / 2.000 A

Original publication on 2015-06-03, revision 1.9


The AS1138 is a single-chip, highly integrated CMOS solution for Power over Ethernet (PoE) Powered Devices requiring input power of up to 30Watts. Applications include Voice over IP (VoIP) Phones, Wireless LAN Access Point, Security Cameras, WiMAX Terminals, Point-of-Sales Terminals, RFID Readers, Thin Clients and Notebook computers.The AS1138 integrates input surge protection, a PD controller and a low-emission DC-DC controller. The AS1138 implements all of the physical layer Powered Device (PD) functionality, as required by IEEE® 802.3af-2005 and IEEE® 802.3at-2009 standards. This includes 2-event classification, Type 2 PSE detection indicator (ATDET), PD detection, under-voltage lock out (UVLO), and Hot- Swap FET integration.The AS1138 has been architected to address both EM emission concerns and surge/over-voltage protection in PoE applications. The chip implements many design features that minimize transmission of system common-mode noise onto the Unshielded Twisted Pair (UTP). On-chip integration of surge protection provides faster response to surge events and limits stray surgecurrent from passing through sensitive circuits, such as the Ethernet PHY. The device is designed to provide safe, lowimpedance discharge paths directly to the earth ground, resulting in superior reliability and circuit protection.


  • Full support of both IEEE® Std. 802.3af-2005 and IEEE®Std. 802.3at-2009 power requirements
  • “2-Event” classification for 802.3at higher power PDs Robust Type 2 PSE detector with proprietary digital filteringfor line noise to eliminate false positives IEC 61000-4-2/3/4/5/6 requirements for EMC Compliance Integrated Surge Protection for 15kV/8kV System level ESDCompliance Integrated DC-DC controller for exceptional EMI performance Programmable DC current limit up to 720mA for 30Wapplications Seamless support for local power, down to 9.5V Implemented in robust 100V automotive process Low Rds-on Hot-Swap FET (typical 0.8Ω) Integrated Short-Circuit Protection Over temperature protection Industrial temperature range,
  • 40º to +85ºC 5x5 mm, 20 lead QFN Package, RoHS compliant


  Order Code SPEC Product series L
RDC typ.
Montageart Vin VOut1
(V (AC))
744043100 PDF WE-TPC SMT Tiny Power Inductor 10 1.19 1 95 40 SMT
750310031 PDF MID-POE Power Over Ethernet Transformers SMT 33 - 57 V (DC) 12 0.58 8 264 3.49:1:0.71 1500 200 13.34 15.24 11.43
750816531 PDF Offline Transformer, WE-UNIT

Other applications and Würth Elektronik products for this IC

  • AS1138
    Topology: Buck, Input Voltage (min.): 41.00 V, Input Voltage (max.): 57.00 V, Switching Frequency (min.): 80.00 kHz, Switching Frequency (max.): 550.00 kHz, Output 1: 3.24 V / 6.800 A